This invention relates to lighting fixtures for discharge lamps having high brightness and linear arcs in general and more particularly to an improved lighting fixture of this nature which achieves almost complete rotational symmetry of the light distribution pattern.
A lighting fixture for a discharge lamp having high brightness and having a linear arc and which has a reflector in the form of a truncated pyramid with a rectangular light egress opening is disclosed in U.S. Pat. No. 3,433,941. In this lamp, which has a square light egress opening, a mercury vapor discharge lamp is arranged so that its axis extends parallel to one side of the light egress opening. With a design of this nature, substantial deviations from a rotationally symmetrical light distribution must be tolerated. However, in many applications such is undesirable. In view of this, it is the object of the present invention to provide an improved lighting fixture of this nature which retains the advantages associated therewith and at the same time provides an essentially rotationally symmetrical light distribution pattern in the horizontal plane [essentially the same light distribution in all vertical planes].